public interface Ordered {
/**
* Useful constant for the highest precedence value.
*
* @see java.lang.Integer#MIN_VALUE
*/
int HIGHEST_PRECEDENCE = Integer.MIN_VALUE;
/**
* Useful constant for the lowest precedence value.
*
* @see java.lang.Integer#MAX_VALUE
*/
int LOWEST_PRECEDENCE = Integer.MAX_VALUE;
/**
* 默认值
*/
int DEFAULT_PRECEDENCE = 0;
/**
* Return the order value of this object, with a
* higher value meaning greater in terms of sorting.
* <p>Normally starting with 0 or 1, with {@link #LOWEST_PRECEDENCE}
* indicating greatest. Same order values will result in arbitrary
* positions for the affected objects.
* <p>Higher value can be interpreted as lower priority,
* consequently the first object has highest priority
* (somewhat analogous to Servlet "load-on-startup" values).
* <p>Note that order values below 0 are reserved for framework
* purposes. Application-specified values should always be 0 or
* greater, with only framework components (internal or third-party)
* supposed to use lower values.
*
* @return the order value
* @see #LOWEST_PRECEDENCE
*/
int getOrder();
}
public class OrderUtil {
public static void order(List<? extends Ordered> orderList) {
Collections.sort(orderList, new Comparator<Ordered>() {
public int compare(Ordered o1, Ordered o2) {
if (o1 != null && o2 != null) {
return o1.getOrder() > o2.getOrder() ? 1
: (o1.getOrder() == o2.getOrder() ? 0 : -1);
}
return 0;
}
});
}
}